|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1995 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1994 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1993 : ¥1,200,000 (Direct Cost : ¥1,200,000)
In this research, effects of presteaming under super-heated water vapor above 100ﾟC on permeability and basic qualities (color, shrinkage and strength) of several soft-and hardwoods were investigated.
Results obtained are as follows ;
1) Staining dark hue and lowering strength properties of wood always were accompanied by the presteaming and degree of such deterioration became stepwise large with increasing steaming temperature. Considering practical use of treated wood, therefore, the upperest limit of presteaming temperature adapted was 140ﾟC for softwood and 120ﾟC for hardwood.
2) Improvement of the permeability of wood according to the treatment was evaluated by longitudinal water adsorption, longitudinal gas permeability, drying rate and amount of impregnation. The permeability of treated wood increased with increasing temperature and duaration of the treatment, that is, with progress of the deterioration mentiond above. Microscopic observations showed that the increase of permeability was caused by break of aspirated pit membranes or removal of some incrusted materials on pit membraines for softwood, and by break of tyloses in vessel for hardwood.
3) In order to minimize the detorioration of wood accompanied by presteaming, new treating procedure which acts high compressed air for short duaration immediately after steaming was attemped. In results of impregnation test, it was found that amount of impregnation of soft-wood lumber treated by the new techniqe of which steaming condition at 120ﾟC for 30min was greater than that of treated by the ordinary presteaming at 140ﾟC for 4hr. It may by evaluated that the new treating procedure is available in practical wood processing such as drying and impregnation fields.